<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <script>
    function toUpperCase(str) {
      return str.toUpperCase()
    }

    function addNum(str) {
      return str + '123'
    }

    function addPoint(str) {
      return str + '...'
    }

    function compose(...arg) {
      return function (x) {
        let res = x
        for(const fn of arg) {
          console.log(fn.toString())
          res = fn(res)
        }
        return res
      }
    }

    const f = compose(addNum, toUpperCase, addPoint)
    console.log(f('wgf'))
  </script>
</body>
</html>